The present invention relates to an apparatus for the detection and resolution from above the surface of the earth buried metallic and nonmetallic objects hereinafter termed "targets".
Other radar-type systems have been suggested for locating and resolving buried targets as typified by U.S. Pat. No. 3,775,765. This patent discloses a system whereby buried targets are detected by the employment of an antenna assembly in contact with the ground and having an impedance approximately equal to that of the ground. A system of this type requires a coarse and fine impedance matching system in order to maximize the transmitter signal coupling into the soil, to minimize the unwanted soil surface reflection and then to maximize the signal return from buried objects. This is accomplished by employing a dielectric lens for coarse impedance matching and a variable matching network driven by a feedback loop for the fine impedance matching.
In contrast; the system of the present invention achieves similar objectives by means of the generation of a true short pulse for the transmitted signal and by means of range gating out the unwanted soil surface reflection. In other words, the system of the present invention does not require additional and complicated structure for matching the impedance of the soil under varying conditions but, rather, employs circuitry which has a high enough resolution capability to distinguish the strong soil reflections from the desired buried object reflections.
The above advantages of the present invention, as well as others, will become apparent as the following detailed description thereof proceeds when taken in conjunction with the accompanying drawings wherein: